Large basins, called depositing sites (or collection basins or containment structures), are built in the vicinity of coastal zones for the purpose of containing the materials resulting from dredging and reclamation activities.
Legislation in many countries regulate activities associated with dredging and reclamation. For example, current legislation in Italy governing the performance requisites for depositing sites (Law No. 84 dated 28 Jan. 1994, as updated by Law No. 296 dated 27 Dec. 2006, Art. 1, par. 996 and 997), stipulates that depositing sites must have a natural or artificially constructed waterproofing system around the perimeter and on the bottom, able to ensure given permeability characteristics at least equivalent to: K (permeability or hydraulic conductivity coefficient)≦1.0×10−9 m/s and thickness greater than or equal to 1 m. Owing to the difficulty of constructing a waterproofing layer satisfying the aforementioned minimum requirements with regard to thickness, it is considered in some cases that the aforementioned legislation might be complied with by simply laying waterproof geomembranes with an overall thickness of a few centimeters, which, while having waterproofing characteristics which comply with the minimum requirements, are less reliable.